1. Field of the Invention
The present invention relates to a reflector and a liquid crystal display device having asymmetrical concave portions, and more particularly to a reflector capable of preventing the moiré patterns from being generated by orienting the axis of the concave portion in a particular direction.
2. Description of the Related Art
A reflective liquid crystal display device is a liquid crystal display device using illumination light such as solar light or a front light as a light source and is mainly used in a portable information terminal requiring low power. Also, as another example, there is a semi-reflective liquid crystal display device. This is a liquid crystal display device which operates in a transmission mode by lighting an internal back light unit when external light can not be sufficiently obtained and operates in a reflection mode by extinguishing the back light unit when external light can be sufficiently obtained, and is mainly used in portable electronics such as a portable telephone or a notebook computer.
In the above-mentioned reflective liquid crystal device, there should be a reflector which reflects external light or front light, or transmits back light while reflecting external light. A conventional reflector is, for example, disclosed in the next Patent Document 1.
Japanese Unexamined Patent Application Publication No. 2003-15129
FIG. 16 shows the perspective view of the reflector disclosed in Patent Document 1. As shown in FIG. 16, the conventional reflector 130 is provided with concave portions 128b . . . adjacent to each other and having a plurality of reflectivities in the surface S of the plate-shaped base member 128 thereof. In addition, the base member 128 is formed with a reflective film 128a such as an Al film. As shown in FIG. 17A, the concave portion 128b is divided by a contour comprising a first curve 128c on one peripheral portion S1 side and a second curve 128d on the other peripheral portion S2 side along a boundary line E.
Further, as shown in FIG. 17B, which is sectional view taken along line G-G, the first curve 128c is connected from the peripheral portion S1 to the boundary line E through a deepest point D S1 and the second curve 128d is connected from the boundary line E to the other peripheral portion S2 and is continuous with the first curve 128c. 
Also, as shown in FIG. 17A, the contour of the concave portion is symmetrical across the axis of line G-G in drawings. In other words, the section along line G-G is the plane of symmetry of the concave portion.
Next, as shown in FIGS. 17 and 18, when the direction parallel with line G-G in FIG. 17A is defined as an axis direction L3 of the concave portion, the axis directions L3 of the concave portions 128b are set to be equal to each other. As shown in FIG. 18, when mounting the reflector on a liquid crystal display panel, the arrangement direction x of the pixel P formed in the liquid crystal display panel is equal to the axis direction L3 of the concave portion 128b. 
In a conventional liquid crystal display device, since a plurality of concave portions 128b each having a concave curved surface is mounted on the reflector 130, the bright display range can be widely ensured and the reflection can be controlled.
However, in the conventional liquid crystal display device, since the arrangement direction x of the pixel P formed in the liquid crystal display panel is equal to the axis direction L3 of the concave portion 128b, there is a problem in that an interference pattern of the light is apt to be generated between the reflector and the liquid crystal display panel, or moiré lines or rainbow color is apt to be generated.
In order to prevent the moiré effect, it is required that the reflector is obliquely mounted with respect to the liquid crystal display panel so that the angle between the arrangement direction x of the pixel P and the axis direction L3 of the concave portion 128b becomes a predetermined moiré angle. When employing this structure, because the direction of the reflective surface is deviated, there was a problem that it is difficult to achieve the desired reflection characteristics of the reflector.